Tsunami Basics

A tsunami is a series of waves formed in a body of water by the sudden displacement of the entire water column. Most large tsunamis are caused by undersea earthquakes, though landslides, volcanic eruptions, explosions, and even meteorite impacts can also cause them. Tsunamis commonly appear on shore as a rapidly receding tide or rapidly rising flood. Tsunamis sometimes provide natural warning signs to people living on coasts, especially close to the tsunami-causing event, such as a rapidly receding tide prior to the waves' arrival. Global monitoring systems also provide critical early warning to coastal populations.[1]

Why do tsunamis matter?

Tsunamis can be highly destructive, causing extensive loss of life and property damage. They have killed more than 350 people on the coast of the United States since 1946, with losses exceeding half a billion dollars.[2] Even larger tsunamis, like the ones that devastated Chile in 1960, Japan in 2011, and Indonesia in 2004, have hit the U.S. Pacific coastal states in the past and could hit them again.

How can geoscience help inform decisions about tsunami hazards?

Tsunamis can’t be prevented, but scientists use earthquake information, tide gauges, and tsunami detection buoys to issue early warnings and give people time to evacuate. Others study records of prehistoric tsunamis left in the geologic record along coasts. These studies help determine the probability of tsunamis on different coastlines, leading to better hazard planning and preparedness. Some geoscientists study the shape and topography of coastal regions to determine the areas likely to be flooded during a tsunami of a given size, which helps to further refine hazard mitigation and evacuation plans.

The Tsunami Evacuation Map from the Washington Division of Geology and Earth Resources provides a large amount of information about tsunami evacuation procedures for the state of Washington. Each of the shaded areas in the image above can be zoomed in on for more detailed information including...

The Tsunami Evacuation Map from the Washington Division of Geology and Earth Resources provides a large amount of information about tsunami evacuation procedures for the state of Washington. Each of the shaded areas in the image above can be zoomed in on for more detailed information including...

The Government of Puerto Rico's Portal Datos Geograficos Gubernamentales (governmental geographic data portal) provides a range of information on natural hazards and resources in Puerto Rico, which can be viewed in a GIS program. The interactive map includes:
Lakes, rivers, and streams...

The Government of Puerto Rico's Portal Datos Geograficos Gubernamentales (governmental geographic data portal) provides a range of information on natural hazards and resources in Puerto Rico, which can be viewed in a GIS program. The interactive map includes:
Lakes, rivers, and streams...

The National Oceanic and Atmospheric Administration's natural hazards viewer shows a variety of recent and historic natural hazards around the world. The interactive map provides data for a range of natural hazards, including tsunamis, volcanic eruptions, and earthquakes. Users can select...

The National Oceanic and Atmospheric Administration's natural hazards viewer shows a variety of recent and historic natural hazards around the world. The interactive map provides data for a range of natural hazards, including tsunamis, volcanic eruptions, and earthquakes. Users can select...

The National Ocean and Atmospheric Administration's tsunami travel times map displays the estimated pre-computed tsunami travel times to select coastal locations from any point in the ocean. The tsunami travel times displayed are in hours and were calculated using TTT software. It is important to...

The National Ocean and Atmospheric Administration's tsunami travel times map displays the estimated pre-computed tsunami travel times to select coastal locations from any point in the ocean. The tsunami travel times displayed are in hours and were calculated using TTT software. It is important to...

The Oregon Department of Geology and Mineral Industries statewide geohazard viewer, HazVu, provides a way to view a range of geohazards in the state of Oregon,including:
Earthquakes - active faults, historical epicenters, expected shaking, and liquefaction hazards
Tsunami inundation hazard...

The Oregon Department of Geology and Mineral Industries statewide geohazard viewer, HazVu, provides a way to view a range of geohazards in the state of Oregon,including:
Earthquakes - active faults, historical epicenters, expected shaking, and liquefaction hazards
Tsunami inundation hazard...